Japanese Sentence Structure Questions 1 (JSSQ)

My first question is about the lesson below.

I was wonder about" わたしは さおりと いい ます". Is " と いい ます" informal way of saying" わたし はさおりです".

My second question is about the usage of watashi in hiragana and kanji in the lesson below.
わたし 私

Is it optional to the person to use the hiragana or kanji version of the word.